The present invention relates to a memory package system in which data is written or read out by a contactless induction coupling between a memory module having a memory therein and a write/ read unit.
In now abandoned U.S. application Ser. No. 07/048832, 07/053759 and in U.S. Pat. No. 4,821,198, the inventors of the present invention have already proposed a system in which in order to write and read data into and out of a non-volatile memory such as an EEPROM which is provided in a memory module by using a write/read unit in a contactless manner, induction coils are provided in both the write/read unit and the memory module, and when data is written in or read out, both of the induction coils are arranged so as to face each other at a predetermined gap interval and both electrical power for operation and serially transmitted write/read data are supplied to the memory module by electromagnetic induction coupling.
In such a power supply to the memory module and a data transmission to write or read in the contactless induction coupling system, when the kinds of signals increase, the number of induction coils in the write/read unit and memory module increases. Therefore, in the above-noted system, a start-stop communication system which does not need to transmit transmission/reception sync clocks (shift clocks) is used as a communication system for transmitting serial data and for converting same into parallel data. That is, it is sufficient that three kinds of signals consisting of a power source signal which is transmitted from the write/read unit to the memory module, an up-signal to write or read, and a down-signal serving as read data which is returned from the memory module to the write/read unit are transmitted between the write/read unit and the memory module.
Furthermore, to reduce the number of induction coils, when the power source signal and up-signal are transmitted to the memory module, they are multiplexed by using the same induction coil. It is sufficient to use two sets of induction coils consisting of a pair of induction coils for the power source signal and up-signal and another pair of induction coils for the down signal.
However, in the start-stop communication system, a communication control circuit for a start-stop communication control which is known as a USART needs to be provided for each of the write/read unit and memory module. In such a type of memory package system, the miniaturization of the memory module is required. However, the start-stop communication system has a problem in that the memory module increases in size by only the amount corresponding to the communication control circuits which are necessary.
On the other hand, in the start-stop communication control system, since the shift clocks reproduced from a reception signal and data bits received are synchronized and the received serial data is converted into the parallel data, a data error easily occurs as compared with the case of using transmission/reception sync clocks. Therefore, it is certainly necessary to perform an error control method such as a parity check or the like. There is also a problem in that when an error is detected, a retransmission request is repetitively generated until the correct data can be received, so that the communication time to write or read becomes long.